Highly-accurate control over in-wheel motor drive assemblies can be achieved by estimating the state of contact between a wheel and a road surface. To estimate the contact state between the wheel and the road surface, conventionally adopted methods include measuring the load imposed on the main body of an in-wheel motor drive assembly by a load sensor mounted on the main body of the in-wheel motor drive assembly. Such an in-wheel motor drive assembly is disclosed, for example, in PTL 1.